The present invention is directed to an apparatus, system, unit or device and method for the automatic suppression of fires. More particularly, the invention is directed to a unit for use in fire suppression where space and/or quantity of available suppressant is limited by necessity, cost, location, or desire for environmental protection. The invention has utility in applications such as fire suppression in confined spaces, aircraft cargo areas, on cook stoves, ranges, in utility rooms, heating and air closets, water heater closets, electrical control rooms, storage rooms, and can be adapted for use in laboratory hoods or any other area of potential fire hazard.
Fire extinguishing systems for cook stove or range hoods are shown in U.S. Pat. No. 3,653,443, issued to Dockery on Apr. 4, 1972; U.S. Pat. No. 4,773,485, issued to Silverman on Sep. 27, 1988; U.S. Pat. No. 4,813,487, issued to Mikulec et al. on Mar. 21, 1989; U.S. Pat. No. 4,830,116, issued to Walden et al. on May 16, 1989; U.S. Pat. No. 4,834,188, issued to Silverman on May 30, 1989; U.S. Pat. No. 4,979,572, issued to Mikulec on Dec. 25, 1990; and U.S. Pat. No. 5,351,760, issued to Tabor, Jr. on Oct. 4, 1994, each of which are hereby incorporated by reference.
U.S. Pat. No. 3,653,443 to Dockery (Dockery '443 or U.S. Pat. No. 3,653,443) discloses a pressure tank-type fire extinguishing system for use in the hood of a cooking range which uses a solenoid operated valve to fully discharge all of the extinguishing fluid in the tank, and provide a control signal to shut off electricity or gas supply to the cooking range burners. The system also provides control of an exhaust fan to expel fumes and smoke, an alarm circuit, and has manually controlled set and reset switches. The system can be manually reset or deactivated during the extinguishing discharge operation by pressing the reset switch. Once the system has been manually reset, the system will be automatically operated again if the thermostats indicate excessive temperatures. Dockery '443 has a particular disadvantage in that it is not easily retrofitted into an existing hood on a cooking range.
U.S. Pat. No. 4,773,485 to Silverman (Silverman '485 or U.S. Pat. No. 4,773,485) discloses a fire extinguishing system for use in a hood of a cooking range which includes a fire extinguisher and a pair of nozzles to disperse the extinguishing material. This system is controlled by a fusible link cable system which has a fusible link which melts in reaction to a fire and allows for a controlling actuator to move and allow the extinguishing system to release its full charge of fire suppressant. Silverman '485 has several disadvantages in that the system is complicated, has many moving parts, is not self-contained, and requires extensive modification to install inside the hood of a cooking range.
U.S. Pat. No. 4,813,487 to Mikulec (Mikulec et al. '487 or U.S. Pat. No. 4,813,487) discloses a fusible link, pressure vessel, fire extinguishing device. Also the system uses a micro-switch to activate a stove shut off mechanism to stop the flow of electricity to the stove if the fire extinguishing system is activated. The system uses a light emitting diode to provide a visual check that the system is operating properly during periods of inactivity. This system also uses multiple release nozzles, a one-shot fusible control link to detect heat, and discharges all of the extinguishing media onto the fire. Mikulec '487 has several disadvantages in that the system is complicated, requires substantial amounts of room behind the existing hood and the angle of mounting is limited.
U.S. Pat. No. 4,830,116 to Walden (Walden et al. '116 or U.S. Pat. No. 4,830,116) discloses another fire extinguisher for a stove hood with the pressure canisters located remotely from the hood and which shuts off the electric or gas supply to the stove in the event of a fire. This system uses heat sensors in the hood to activate the discharge of gaseous or liquid fire extinguishing agents, operate an exhaust fan, and activate an alarm system. This system also discharges the extinguishing agent in one release and utilizes an intermediate source of power to maintain the open position of the discharge controlling solenoids regardless of the temperatures sensed after activation has occurred. The discharge is maintained in the first pressure canister until it is almost completely discharged. When the first canister's discharge drops its internal pressure to 25 psi, a second pressure canister is also turned on. When the second canister drops to 25 psi, a delay timer for the exhaust fan is turned on. This delay allows for the canisters to complete their discharge and ensures that the exhaust fan is not turned on until both canisters are completely discharged.
U.S. Pat. No. 4,834,188 to Silverman (Silverman '188 or U.S. Pat. No. 4,834,188) like Silverman '485 described above discloses a fire extinguishing system having fused link cable control system for discharging a complete supply of pressure canister-type fire extinguisher onto a stovetop upon activation of the system. Silverman '188 has several disadvantages in that the system is complicated, is not self-contained, and requires extensive modification to install inside an existing hood for a cooking range.
U.S. Pat. No. 4,979,572 to Mikulec (Mikulec '572 or U.S. Pat. No. 4,979,572) like Mikulec '487 described above discloses an automatically activated fire extinguishing device for a stove. Mikulec '572 has several disadvantages in that the system is complicated, requires substantial room behind the existing hood, and the angle of mounting is limited.
U.S. Pat. No. 5,351,760 to Tabor, Jr. (Tabor, Jr. '760 or U.S. Pat. No. 5,351,760) discloses a pressure canister-type fire suppression system for use with a cook stove or range and which operates in several modes or stages to warn of, prevent, and extinguish stovetop fires. On sensing a first temperature increase, a fan is switched on. At a second temperature, an alarm is activated. At a third temperature, the stove is shut down. A fusible link is designed to melt at a temperature higher than the third temperature so that provisional measures may be activated prior to the dispensing of the fire retardant. The Tabor, Jr. fire suppression system is relatively complex and includes numerous working parts which are subject to failure, and the entire contents in the fire retardant canister are dispensed when the activation cable link melts. In accordance with a preferred embodiment, the fire retardant is a liquid potassium salt solution charged to approximately 195 psi and regulated to dispense through the nozzles at about 60 psi and at a droplet size of approximately 900 microns. The Tabor, Jr. '760 system requires an outside electrical energy supply in order to be operational, requires extensive hard wired components which are subject to damage, and makes retrofitting difficult due to problems in placing new wiring inside walls of existing structures.
All of the known pressure canister-type systems have particular disadvantages, such as those listed above. Typical high pressure canister-type systems depend on a cable system fusible link or thermal link-type of activation. Such a thermal link responds to elevated temperature by melting to activate the system. Once activated (melted), the system does not and cannot automatically reset. Thus, the canister-type systems will, if not manually interrupted, continuously disperse the fire suppressant until the charge is extinguished. This continuous discharge results in possible waste of extinguishing material, does not allow for a second or third discharge, and may lead to excessive damage to the environment and the protected structure.
Known high pressure canister-type systems which utilize environmentally unfriendly chemicals, such as Halon, also rely on a thermal link-type of activation system which releases all available fire suppressant, thus increasing the environmental impact in the event of a discharge. Other known high pressure canister systems require electrical power for system activation or reset, thus rendering these systems at least partially ineffective should a power loss occur.
The above-described fire extinguishing devices suffer from the drawbacks of being overly complicated, having numerous parts which are susceptible to failure, allow only one discharge of fire extinguishing material unless they are manually shut off during operation, are not environmentally friendly, and unless a manual reset is accomplished during the first activation, cannot automatically react to re-ignition of the fire that is to be extinguished. Further, the systems disclosed in the patents above do not appear to provide for an automatic fire retardant chemical or agent shut off following an initial discharge of fire retardant by sensing a reduction in temperature.
This "one shot" activation renders the conventional systems completely ineffective if a re-ignition should occur. Also, all known systems utilize a hard wired system of shutting down the stove's energy source. This makes the prospect of retrofit into an existing hood difficult. This hard wiring adds difficulty in retrofitting existing hoods or installing new hoods due to the routing of wiring through existing walls or the unsightliness of exposed wireways which makes these systems undesirable. Other known systems require electrical power for system activation or reset, thus rendering these systems at least partially ineffective should a power loss occur.
Water-based, piped, fire extinguishing and protection system sprinkler head-type controls or valves are disclosed in U.S. Pat. No. 3,857,446, issued to Kenny on Dec. 31, 1974; and U.S. Pat. No. 3,861,473, issued to Livingston on Jan. 21, 1975, each of which are hereby incorporated by reference.
U.S. Pat. No. 3,857,446 to Kenny (Kenny '446 or U.S. Pat. No. 3,857,446) discloses an actuator piston and a bi-metallic coil temperature sensitive actuator each used in a different water supply-type fire extinguishing sprinkler control to open and close sprinkler valves at predetermined temperatures. Kenny '446 uses a spring-loaded, snap action valve to open and close the sprinkler systems in response to the slow movement of a temperature sensitive actuator and locates the valve in the high temperature fire hazard area.
U.S. Pat. No. 3,861,473 to Livingston (Livingston '473 or U.S. Pat. No. 3,861,473) discloses another type of temperature sensitive actuator used in a water supply-type fire extinguishing sprinkler control to open and close sprinkler valves at predetermined temperatures. Livingston uses a thermovalve motor, gate valve member, and a pressurized gas flow control unit for controlling the dispersion of water. This system reduces the water demand on the system in low pressure situations so that only those areas in critical need, where the temperature has exceeded 500 degrees F., are supplied with water.
The above-described fire extinguishing devices suffer from the drawbacks of placing the valve and water supply directly in the high temperature area that is exposed to the fire hazard. Special adaptations for the reduction of grease and other types of buildup are therefore necessary to maintain the long term operable life of the extinguishing unit. Furthermore, these system are limited in their applicability because they do not provide for a simple, self-contained, transportable, or retrofit system for fire extinguishing protection. Nor do these water-based systems provide for a way to disconnect a heat source or operate an alarm.
Commercially available industrial powder or dry chemical fire extinguishing systems for use in restaurants and the like do not provide for the shutting off of the stove, the sounding of an alarm, or the cessation of discharge of the fire retardant chemical or agent upon extinguishment of the fire.
Hence, there is a need for an eloquently simple, high pressure, self-contained, canister-type fire extinguishing or suppression system with an automatic controlling system which releases only the amount of extinguishing agent which is necessary to extinguish the fire, limits the discharge of environmentally unfriendly materials in the event of a fire, retains any remaining extinguishing agent for use in case of a re-ignition or subsequent fire, is operable to suppress fires regardless of the condition of external power sources, can control and remove heat sources from the fire hazard area, which facilitates retrofitting thereof, and/or can provide for an alarm.